Development of a Coagulation Disorders Unit.

Our Coagulation Disorders Unit in Helsinki, Finland, provides 24/7 services for local and national hospitals and colleagues upon requests regarding bleeding and thrombosis diagnostics and management, including follow-up. The unit has a tight connection between the clinic and laboratory, and its maintenance and sharing knowledge and observations have been priorities, already for over 20 years and will continue to be of major importance. The consultation service is provided by phone during daytime and on-call hours, and in written form sent electronically to the consulting stakeholders. Thrombosis and hemostasis-targeted outpatient clinics are also available for the patients referred to the center. Writing local guidance and official guidelines, Nordic, European and international collaboration, and educational activities including social communication are critical elements for the Coagulation Disorders Unit. Alertness to acute coagulation abnormalities, such as occurred during COVID-19 and vaccine-induced thrombosis and thrombocytopenia, and development of strategies to manage cross-disciplinary problems are topics which call upon broad networking. The Nordic community has an ongoing historical meeting, which has been circulating among coagulation centers for the past 56 years. At the European level, the European Association of Haemophilia and Allied Disorders focuses on bleeding disorders and their management, including safety surveillance. The International Society of Thrombosis and Haemostasis offers excellent basic and clinical benchmarks for any Coagulation Disorders Unit. We hope that the description of the development and implementation of our Coagulation Disorders Unit in Helsinki achieves international interest and broadens international collaboration. Finally, we congratulate STH on its great contributions around the globe and for providing a vivid forum to foster the discipline of thrombosis and hemostasis.

Increased circulating platelet-derived extracellular vesicles in severe COVID-19 disease.

Coagulation disturbances are major contributors to COVID-19 pathogenicity, but limited data exist on the involvement of extracellular vesicles (EVs) and residual cells (RCs). Fifty hospitalized COVID-19 patients stratified by their D-dimer levels into high (>1.5 mg/L, n = 15) or low (≤1.5 mg/l, n = 35) and 10 healthy controls were assessed for medium-sized EVs (mEVs; 200-1000 nm) and large EVs/RCs (1000-4000 nm) by high sensitivity flow cytometry. EVs were analyzed for CD61, CD235a, CD45, and CD31, commonly used to detect platelets, red blood cells, leukocytes or endothelial cells, respectively, whilst phosphatidyl serine EVs/RCs were detected by lactadherin-binding implicating procoagulant catalytic surface. Small EV detection (sEVs; 50-200 nm) and CD41a (platelet integrin) colocalization with general EV markers CD9, CD63, and CD81 were performed by single particle interferometric reflectance imaging sensor. Patients with increased D-dimer exhibited the highest number of RCs and sEVs irrespective of cell origin (p < .05). Platelet activation, reflected by increased CD61+ and lactadherin+ mEV and RC levels, associated with coagulation disturbances. Patients with low D-dimer could be discriminated from controls by tetraspanin signatures of the CD41a+ sEVs, suggesting the changes in the circulating platelet sEV subpopulations may offer added prognostic value during COVID progression.

What is the context? Coronavirus disease 19 (COVID-19) frequently leads to blood clotting disturbances, including thromboses.Particles smaller than cells, extracellular vesicles (EVs), and residual cells (RCs) affect blood clotting, but data on their role and diagnostic utility in COVID-19 are sparse.What is new? In this study, we assessed 50 hospitalized COVID-19 patients and 10 healthy controls for their different EV subpopulations and residual cells (50­4000 nm).Blood clotting marker D-dimer, which is elevated in severe COVID-19 infection, was used to characterize disease severity and stratify the patient subgroups. Fifteen patients (30%) with high D-dimer (>1.5 mg/L) were compared to controls, and 35 patients with lower D-dimer (≤1.5 mg/mL).The most topical state-of-the-art methods for detection of EV subpopulations, that is, high sensitivity flow cytometry (hsFCM) and single particle interferometric reflectance imaging sensor (SP-IRIS), were used with markers indicative of platelet, red blood cell, leukocyte or endothelial cells. The subpopulations differentiated by platelet and tetraspanin signatures by hsFCM and SP-IRIS, respectively.The main findings are Patients with high D-dimer systematically exhibited the highest number of platelet EVs in all subpopulations (p < .05).Small EVs subpopulations (differentiated by the tetraspanin signatures) could discriminate patients with low D-dimer (p < .001) from healthy controls.Differences between the two D-dimer groups were seen in the platelet-derived (large and medium EVs and RCs), RBC-derived mEVs and l EVs and RCs, and lactadherin-positive large EVs and RCs (p < .05).What is the impact? Platelet activation, reflected by increased EVs was associated with blood clotting disturbances. Small EVs signatures revealed changes in the EV subpopulations in association with blood clotting during COVID-19. Such signatures may enable identification of severely ill patients before the increase in coagulation is evident by coagulation parameters, for example, by high D-dimer.

In vitro comparison of cold-stored whole blood and reconstituted whole blood.

BACKGROUND AND OBJECTIVES: Cold-stored whole blood (CSWB) is increasingly used in damage control resuscitation. Haemostatic function of CSWB seems superior to that of reconstituted whole blood, and it is sufficiently preserved for 14-21 days. To provide evidence for a yet insufficiently studied aspect of prehospital CSWB use, we compared in vitro haemostatic properties of CSWB and currently used in-hospital and prehospital blood component therapies. MATERIALS AND METHODS: Blood was obtained from 24 O RhD positive male donors. Three products were prepared: CSWB, in-hospital component therapy (red blood cells [RBCs], OctaplasLG and platelets 1:1:1) and prehospital component therapy (RBCs and lyophilized plasma 1:1). Samples were drawn on days 1 and 14 of CSWB or RBC cold storage. On day 14, platelet concentrates at their expiry (5 days) were used for 1:1:1 mixing. Conventional clotting assays, rotational thromboelastometry, thrombin formation and platelet function were assessed. RESULTS: Haemoglobin, platelet count, fibrinogen and coagulation factor levels remained closest to physiological in CSWB. Factor VIII activity decreased markedly by day 14 in CSWB. The decline in platelet function was prominent in CSWB. However, CSWB on day 14 yielded physiological EXTEM MCF, suggesting haemostatically sufficient platelet function. Despite haemodilution and lower coagulation factor levels, in-hospital component therapy was haemostatically adequate. Prehospital component therapy formed the weakest clots. Thrombin formation potential remained comparable and stable in all groups. CONCLUSION: Current prehospital component therapy fails to offer the clotting potential that CSWB does. CSWB and current in-hospital 1:1:1 component therapy show similar haemostatic potential until 14 days of storage.

Verifying measurements on Siemens Atellica® instruments using clinically acceptable analytical performance specifications.

Measurements on clinical chemistry analysers must be verified to demonstrate applicability to their intended clinical use. We verified the performance of measurements on the Siemens Atellica® Solution chemistry analysers against the clinically acceptable analytical performance specifications, CAAPS, including the component of intra-individual biological variation, CVI. The relative standard uncertainty of measurement, i.e. analytical variation, CVA, was estimated for six example measurands, haemoglobin A1c in whole blood (B-HbA1c), albumin in urine (U-Alb), and the following measurands in plasma: sodium (P-Na), pancreatic amylase (P-AmylP), low-density lipoprotein cholesterol (P-LDL-C), and creatinine (P-Crea). Experimental CVA was calculated from single-instrument imprecision using control samples, variation between measurements on parallel instruments, and estimation of bias with pooled patient specimens. Each obtained CVA was compared with previously developed CAAPS. The calculated CVA was 1.4% for B-HbA1c (CAAPS 1.9% for single diagnostic testing, CAAPS 2.0% for monitoring after duplicate tests; IFCC units), 10.9% for U-Alb (CAAPS 44.9%), 1.2% for P-Na (CAAPS 0.6%, after triplicate testing 1.5%), 8.2% for P-AmylP (CAAPS 22.9%). The CVA was 4.9% for P-LDL-C (CAAPS for cardiovascular risk stratification 4.9% after four replicates), and 4.2% for P-Crea (CAAPS 8.0%). Three of the six measurands fulfilled the estimated clinical need. Results from P-Na measurements indicate a general need for improving the P-Na assays for emergency patients. It is necessary to consider CVI when creating diagnostic targets for laboratory tests, as emphasised by the CAAPS estimates of B-HbA1c and P-LDL-C.

Markers of early vascular aging are not associated with cryptogenic ischemic stroke in the young: A case-control study.

BACKGROUND AND PURPOSE: We aimed to assess the association between covert atherosclerosis, arterial stiffness, and early-onset cryptogenic ischemic stroke (CIS) in a prospective case-control study. METHODS: We enrolled 123 young CIS patients (median age 41 years; 42% women) and 123 age- and sex-matched controls. Carotid intima-media thickness (CIMT), Augmentation Index (AIx), central pulse wave velocity (PWV), and subendocardial viability ratio (SEVR) were compared between patients and controls. Conditional logistic regression was used adjusting for age, systolic blood pressure, diastolic blood pressure, current smoking, total cholesterol/high-density lipoprotein cholesterol (Total-C/HDL-C) ratio, and glycated albumin to assess the independent association between CIMT, arterial stiffness and CIS. RESULTS: Patients with higher CIMT and PWV were older, more often men and they had more frequently well-documented risk factors, lower HDL and higher Total-C/HDL-C ratio compared to other tertiles. In univariate comparisons, we found no differences between patients and controls regarding CIMT, AIx, or PWV. In the entire cohort, patients had a significantly lower SEVR compared to controls (146.3%, interquartile range [IQR] 125.7-170.3 vs. 158.0%, IQR 141.3-181.0, P=0.010). SEVR was lower also in women compared to their controls (132.0%, IQR 119.4-156.1 vs. 158.7%, IQR 142.0-182.8, P=0.001) but no significant difference appeared between male patients and male controls. However, after adjusting for comorbidities and laboratory values these significant differences were lost (odds ratio [OR] 1.52, 95% confidence interval [CI] 0.47-4.91) in the entire cohort and OR 3.89, 95% CI 0.30-50.80 in women). CONCLUSIONS: Higher CIMT and PWV were associated to higher age, male sex, and several well-documented cardiovascular risk factors. However, in this study we could not prove that either covert atherosclerosis or arterial stiffness contribute to pathogenesis of early-onset CIS.

Anaemia and enhancement of coagulation are associated with severe COVID-19 infection.

Coagulation disturbances are common in severe COVID-19 infection. We examined laboratory markers in COVID-19 patients during the first wave of the pandemic in Finland. We analysed a wide panel of coagulation tests (IL ACL TOP 750/500®) from anonymously collected samples of 78 hospitalized COVID-19 patients in intensive care units (ICUs; n = 34) or medical wards (n = 44) at Helsinki University Hospital in April-May 2020. These coagulation data were supplemented with the laboratory information system results, including complete blood count and C reactive protein (CRP). Coagulation and inflammatory markers were elevated in most: FVIII in 52%, fibrinogen 77%, D-dimer 74%, CRP 94%, platelet count 37%. Anaemia was common, especially in men (73% vs. 44% in women), and overall weakly correlated with FVIII (women R2 = 0.48, men R2 = 0.24). ICU patients had higher fibrinogen and D-dimer levels (p < .01). Men admitted to the ICU also had higher platelet count, leukocytes and FVIII and lower haemoglobin than the non-ICU patients. None of the patients met the disseminated intravascular coagulation (DIC) criteria, but 31% had a D-dimer level of at least 1.5 mg/L. Presence of both anaemia and high D-dimer together with FVIII is independently associated with ICU admission. Antithrombin was reduced in 47% of the patients but did not distinguish severity. Overall, CRP was associated with coagulation activation. Elevated FVIII, fibrinogen and D-dimer reflected a strong inflammatory response and were characteristic of hospitalized COVID-19 patients. The patients were often anaemic, as is typical in severe inflammation, while anaemia was also associated with coagulation activity.

Warfarin dose requirement in patients having severe thrombosis or thrombophilia.

AIMS: Warfarin dose requirement varies significantly. We compared the clinically established doses based on international normalized ratio (INR) among patients with severe thrombosis and/or thrombophilia with estimates from genetic dosing algorithms. METHODS: Fifty patients with severe thrombosis and/or thrombophilia requiring permanent anticoagulation, referred to the Helsinki University Hospital Coagulation Center, were screened for thrombophilias and genotyped for CYP2C9*2 (c.430C>T, rs1799853), CYP2C9*3 (c.1075A>C, rs1057910) and VKORC1 c.-1639G>A (rs9923231) variants. The warfarin maintenance doses (target INR 2.0-3.0 in 94%, 2.5-3.5 in 6%) were estimated by the Gage and the International Warfarin Pharmacogenetics Consortium (IWPC) algorithms. The individual warfarin maintenance dose was tailored, supplementing estimates with comprehensive clinical evaluation and INR data. RESULTS: Mean patient age was 47 years (range 20-76), and BMI 27 (SD 6), 68% being women. Forty-six (92%) had previous venous or arterial thrombosis, and 26 (52%) had a thrombophilia, with 22% having concurrent aspirin. A total of 40% carried the CYP2C9*2 or *3 allele and 54% carried the VKORC1-1639A allele. The daily mean maintenance dose of warfarin estimated by the Gage algorithm was 5.4 mg (95% CI 4.9-5.9 mg), and by the IWPC algorithm was 5.2 mg (95% CI 4.7-5.7 mg). The daily warfarin maintenance dose after clinical visits and follow-up was higher than the estimates, mean 6.9 mg (95% CI 5.6-8.2 mg, P < 0.006), with highest dose in patients having multiple thrombophilic factors (P < 0.03). CONCLUSIONS: In severe thrombosis and/or thrombophilia, variation in thrombin generation and pharmacodynamics influences warfarin response. Pharmacogenetic dosing algorithms seem to underestimate dose requirement.

Effects of thromboprophylactic doses of apixaban and rivaroxaban on coagulation and thrombin generation in association with total hip replacement.

Factor Xa inhibitors (FXaI) apixaban and rivaroxaban are used for thromboprophylaxis after major elective orthopaedic surgery. Because few patient sample studies exist, we postoperatively assessed patients undergoing unilateral total hip arthroplasty, including 22 treated with apixaban (2.5 mg BID) and 20 treated with rivaroxaban (10 mg OD). We collected blood samples before and 3 h after drug intake at 4 time points, preoperatively, as well as on day 1, week 1 (day 2-8) and day 28 post-operation. APTT and PT were immediately analysed. Calibrated anti-FXa activity, Russel's Viper Venom Time (RVVT) and thrombin generation (TG; Calibrated Automated Thrombogram®) captured the effects of FXaI on coagulation and TG. APTT and PT remained within the reference interval throughout, and did not correlate with FXaI levels (PT R2 = 0.44, APTT R2 = 0.07). Mean apixaban concentration at the peak varied by eightfold (19-153 ng/mL), but rivaroxaban only by 1.5-fold (111-183 ng/mL). Rivaroxaban, but not apixaban prolonged RVVT at peak levels. Both FXaIs had a prolonged lag time of TG (p < 0.001). Rivaroxaban decreased ETP peak at all time points and reached a minimum at day 28 (540 nM/min at rivaroxaban 184 ng/mL, p < 0.001), while rivaroxaban trough levels were low and ETP values normal. However, with apixaban, after an initial decrease, ETP did not differ between peak and trough levels until decreasing on day 28 at peak (990 nM/min at apixaban 112 ng/mL, p = 0.005). In conclusion, due to different dosing and pharmacology rivaroxaban and apixaban distinctly inhibited TG under postoperative conditions.

Activation of endothelium, coagulation and fibrinolysis is enhanced and associates with renal anti-neutrophil cytoplasmic antibody-associated vasculitis.

BACKGROUND: While the incidence of thromboembolism in anti-neutrophil cytoplasmic antibodies-associated vasculitis (AAV) is high, the coagulation and fibrinolysis profile in AAV patients remains poorly characterized. We aimed at studying this profile in association with vasculitis activity and renal function. METHODS: This prospective study included 21 AAV patients with renal disease and 40 controls with other chronic kidney disease. Platelet count, antithrombin, FVIII : C, von Willebrand factor (VWF) activities (VWF : RCo) and antigen (VWF : Ag), fibrinogen, prothrombin fragments (F1 + 2), fibrin degradation product d-dimer and the presence of antiphospholipid antibodies were measured during the active and remission states of the AAV and at the baseline in controls. Occurrence of thromboembolic events was recorded. RESULTS: F1 + 2 was 2.6-fold and D-dimer was 5-fold higher during the active AAV than its remission (median 563 versus 212 pM and 3.0 versus 0.6 mg/L, P = 0.001 for both). FVIII : C (median 228%), VWF : RCo (198%) and VWF : Ag (222%) were the highest among the patients with active AAV and remained elevated also under remission. In active AAV, both F1 + 2 and d-dimer clearly associated with impaired renal function (r = -0.67, P = 0.001 and r = -0.66, P = 0.001). In AAV patients, two thromboembolic events occurred during the follow-up. CONCLUSIONS: In active renal AAV, thrombin formation and especially fibrin turnover prevail compared both with remission and other kidney diseases. Overall, AAV is characterized by an enhanced coagulation, especially FVIII activity, which continues partly in remission.

Laboratory assessment of novel oral anticoagulants: method suitability and variability between coagulation laboratories.

BACKGROUND: Laboratory tests to assess novel oral anticoagulants (NOACs) are under evaluation. Routine monitoring is unnecessary, but under special circumstances bioactivity assessment becomes crucial. We analyzed the effects of NOACs on coagulation tests and the availability of specific assays at different laboratories. METHODS: Plasma samples spiked with dabigatran (Dabi; 120 and 300 µg/L) or rivaroxaban (Riva; 60, 146, and 305 µg/L) were sent to 115 and 38 European laboratories, respectively. International normalized ratio (INR) and activated partial thromboplastin time (APTT) were analyzed for all samples; thrombin time (TT) was analyzed specifically for Dabi and calibrated anti-activated factor X (anti-Xa) activity for Riva. We compared the results with patient samples. RESULTS: Results of Dabi samples were reported by 73 laboratories (13 INR and 9 APTT reagents) and Riva samples by 22 laboratories (5 INR and 4 APTT reagents). Both NOACs increased INR values; the increase was modest, albeit larger, for Dabi, with higher CV, especially with Quick (vs Owren) methods. Both NOACs dose-dependently prolonged the APTT. Again, the prolongation and CVs were larger for Dabi. The INR and APTT results varied reagent-dependently (P < 0.005), with less prolongation in patient samples. TT results (Dabi) and calibrated anti-Xa results (Riva) were reported by only 11 and 8 laboratories, respectively. CONCLUSIONS: The screening tests INR and APTT are suboptimal in assessing NOACs, having high reagent dependence and low sensitivity and specificity. They may provide information, if laboratories recognize their limitations. The variation will likely increase and the sensitivity differ in clinical samples. Specific assays measure NOACs accurately; however, few laboratories applied them.

Grapefruit juice markedly increases the plasma concentrations and antiplatelet effects of ticagrelor in healthy subjects.

AIM: This study examined the effects of grapefruit juice on the new P2Y12 inhibitor ticagrelor, which is a substrate of CYP3A4 and P-glycoprotein. METHODS: In a randomized crossover study, 10 healthy volunteers ingested 200 ml of grapefruit juice or water thrice daily for 4 days. On day 3, they ingested a single 90 mg dose of ticagrelor. RESULTS: Grapefruit juice increased ticagrelor geometric mean peak plasma concentration (Cmax ) to 165% (95% confidence interval 147, 184%) and area under the concentration-time curve (AUC(0,∞)) to 221% of control (95% confidence interval 200, 245%). The Cmax and AUC(0,34 h) (P < 0.05) but not the AUC(0,∞) of the active metabolite C12490XX were decreased significantly. Grapefruit juice had a minor effect on ticagrelor elimination half-life prolonging it from 6.7 to 7.2 h (P = 0.036). In good correlation with the elevated plasma ticagrelor concentrations, grapefruit juice enhanced the antiplatelet effect of ticagrelor, assessed with VerifyNow® and Multiplate® methods, and postponed the recovery of platelet reactivity. CONCLUSIONS: Grapefruit juice increased ticagrelor exposure by more than two-fold, leading to an enhanced and prolonged ticagrelor antiplatelet effect. The grapefruit juice-ticagrelor interaction seems clinically important and indicates the significance of intestinal metabolism to ticagrelor pharmacokinetics.

Laboratory Assessment of Unfractionated Heparin (UFH) with Activated Clotting Time (ACT) and Anti-Xa Activity during Peripheral Arterial Angiographic Procedure.

Activated clotting time (ACT) is used in cardiac surgery for monitoring unfractionated heparin (UFH). In endovascular radiology, ACT use is less established. We aimed to test the validity of ACT in UFH monitoring in endovascular radiology. We recruited 15 patients undergoing endovascular radiologic procedure. ACT was measured with ICT Hemochron® device as point-of-care (1) before standard UFH bolus, (2) immediately after the bolus, and in some cases (3) 1 h into the procedure or a combination thereof (altogether 32 measurements). A total of two different cuvettes, ACT-LR and ACT+ were tested. A reference method of chromogenic anti-Xa was used. Blood count, APTT, thrombin time and antithrombin activity were also measured. UFH levels (anti-Xa) varied between 0.3-2.1 IU/mL (median 0.8) and correlated with ACT-LR moderately (R2 = 0.73). The corresponding ACT-LR values were 146-337 s (median 214). ACT-LR and ACT+ measurements correlated only modestly with one another at this lower UFH level, with ACT-LR being more sensitive. Thrombin time and APTT were unmeasurably high after the UFH dose, rendering them of limited use in this indication. We adopted an ACT target of >200-250 s in endovascular radiology based on this study. While ACT correlation with anti-Xa is suboptimal, the readily available point-of-care nature increases its suitability.

Active online assessment of patients using new oral anticoagulants: bleeding risk, compliance, and coagulation analysis.

Clinicians prescribing new oral anticoagulants (OACs; dabigatran, rivaroxaban, and apixaban) should be aware of the exclusion criteria related to bleeding risks defined in published clinical studies. At least a quarter of patients currently using warfarin have an exclusion criterion that may prevent easy transition to the new OACs. In the summary of product characteristics for dabigatran, as an example, the target populations appear generalized. Due to fixed dosing and predictable pharmacology, routine laboratory monitoring of new OACs is deemed unnecessary. Under special circumstances, however, understanding the extent of thrombin or factor (F) Xa inhibition may aid in evaluating compliance and handling emergency interventions, bleeding complications, or overdoses. Although commonly available global coagulation-time assessments (prothrombin time and activated partial thromboplastin time) are insensitive, they may assist clinical management by indicating a severe accumulation of OACs; moreover, a normal thrombin time (TT) excludes a thrombin-inhibitor effect. In particular circumstances, specific assays (diluted TT, Ecarin clotting time, anti-FIIa or anti-FXa activity) may quantify the anticoagulant effect, but therapeutic ranges for dose adjustment are not yet established. Laboratory results are also influenced by clinical situation: e.g. bleed (consumption of coagulation factors) versus postoperative state (activation of coagulation). Without specific antidotes and evidence-based treatment strategies, new OACs are clinically worrisome in patients with impaired renal or liver function. Postmarketing surveillance and recording of bleeding complications (ICD-10 D68.32) are therefore of major importance.

New insights into von Willebrand disease and platelet function.

Regulation of binding between von Willebrand factor (VWF) and the platelet receptor glycoprotein (GP) Ibα is one of the key steps in controlling hemostasis and thrombosis. On vascular injury at sites of high shear rates, the GPIbα interaction with subendothelial-bound VWF will initiate the tethering of circulating platelets to the vessel wall. Tethered platelets subsequently roll on the damaged vessel wall, a process that is amplified by the activation of the platelet integrin αΙΙbß3 (GPIIb/IIIa). The initial tethering to VWF is rapidly followed by platelet binding to collagen through specific receptors (GPVI and α2ß1), leading to firm adhesion, activation, and additional stable bonds mediated by αΙΙbß3. The above described interactions can result in two distinct processes: physiological hemostasis and pathological thrombosis. Furthermore, VWF carries coagulation factor VIII, which is involved in thrombin formation that in addition to activating platelets, mediates fibrin formation and has several other actions. The importance of VWF in hemostasis is well known in patients suffering from von Willebrand disease (VWD) who present with a defect in both platelet plug and fibrin formation. Type 2B VWD is of special interest as it may provide further insight into the mechanism by which VWF promotes the adhesion of platelets to a thrombogenic surface under conditions of high shear stress. The variant phenotypic manifestations in patients affected with type 2B VWD, however, have raised the question of locus heterogeneity in VWD as a consequence of, for example, additional defects in receptor or signaling proteins mediating platelet adhesion and aggregation. Indeed, quite a few polymorphisms of platelet receptors have been associated with increased bleeding in VWD. However, many aspects of the disease remain to be elucidated. For instance, thrombin and platelet procoagulant activity may be important counterplayers to determine the severity of the bleeding complications associated with VWD.

Novel Ex Vivo DOAC Removal Methods Reduce Interference in Lupus Anticoagulant Testing.

Direct oral anticoagulants (DOAC) interfere in laboratory coagulation testing. The aim here was to study how commercial DOAC removal methods, DOAC Filter® and DOAC-Stop™, perform to eliminate DOAC concentrations and false positive results in lupus anticoagulant (LAC) testing. We acquired 50 patient samples with high concentrations of DOACs: apixaban (n = 18, range 68-572 ng/mL), dabigatran (n = 8, range 47-154 ng/mL), edoxaban (n = 8, range 35-580 ng/mL) and rivaroxaban (n = 16, range 69-285 ng/mL). DOACs were removed ex vivo with either DOAC Filter® (n = 28) or DOAC-Stop™ (n = 22). Additionally, commercial control and calibrator samples were studied (n = 13 for DOAC Filter®, n = 14 for DOAC-Stop™). LAC screening was performed before and after DOAC removal. Both DOAC Filter® and DOAC-Stop™ were effective in removing DOAC concentrations in samples: DOAC concentrations decreased to median of 0 ng/mL (range 0-48 ng/mL). Only one sample had more than residual 25 ng/mL of DOAC (apixaban). Before DOAC removal, 96% (48/50) of patient samples and over 90% (12/13 DOAC Filter®, 13/14 DOAC-Stop™) of control/calibrator samples were positive in the LAC screening. In patient samples, LAC screening turned negative in 61% (17/28) after DOAC Filter® and 45% (10/22) after DOAC-Stop™ treatment. All control samples became negative after DOAC removal. In conclusion, DOAC removal ex vivo reduces false positives in LAC screening. DOAC removal halved the need for confirmation or mixing tests- Although a subset of patients would require further testing, DOAC removal reduces unnecessary repeated LAC testing.

Changing Immunochemistry Platforms: Thyroid Function Test Comparison and Reference Intervals Based on Clinical Needs.

BACKGROUND: Diagnosis of thyroid dysfunction relies on thyroid stimulating hormone (TSH), free thyroxine (FT4), and free tri-iodothyronine (FT3) tests against valid reference intervals (RIs). We changed the immunoassay platform from Abbott Architect to Siemens Atellica and aimed to establish Atellica RIs based on laboratory information system (LIS) patient data. METHODS: Atellica thyroid hormone immunoassays were verified against those of Architect. Real-life patient results were retrieved from LIS. A single result per patient dataset was used to establish the RIs by the indirect method. RESULTS: Atellica and Architect assays correlated well but Atellica showed a positive bias between 13% and 53%, the largest for FT4. Variations of the Atellica assays were ≤4%. The 95% Atellica RIs were 0.4-3.8 mU/L for TSH, 0.9-1.6 ng/dL for FT4, and 227-416 pg/dL for FT3. Considering the accumulating clinical experience with Atellica, the RIs for clinical use were adjusted as 0.5-4.0 mU/L, 0.9-1.8 ng/dL, and 169-409 pg/dL, respectively. CONCLUSIONS: We verified thyroid hormone RIs for Atellica by the indirect method for the first time. Our model proved reliable for selecting results of presumably healthy individuals from LIS data. Critical review of the RIs with local endocrinologists is essential.

Practical viewpoints on the diagnosis and management of heparin-induced thrombocytopenia.

Heparin-induced thrombocytopenia (HIT, type II) is an immune-mediated disorder due to antibodies formed against heparin-platelet factor 4 complexes, usually appearing at days 5 to 14 after initiation of heparin. It is important to recognize HIT because heparin prophylaxis or treatment paradoxically associates with new venous and/or arterial thrombosis. Early clinical suspicion and diagnosis together with proper pharmacotherapy and close laboratory monitoring are the cornerstones for successful management. This includes monitoring of Thrombocytopenia, its Timing to heparin administration, appearance of new Thrombosis or resistance to treatment, and differential diagnosis by exclusion of o Ther causes (the 4T's). Specific attention should be paid to the absence or presence of thrombosis and to tailoring thromboprophylaxis or anticoagulant therapy with a nonheparin alternative. Even in the absence of HIT-associated thrombosis, an active policy for prolonged thromboprophylaxis is demanded. Rapid and reliable assays should be developed for diagnosis and anticoagulation monitoring to secure safe management with nonheparins. Semiquantitative testing for on-call hours should be available and later confirmed as clinically needed. Alternative therapeutic options are available, but because their use is infrequent, experienced coagulation treatment centers should provide guidance in the treatment and in laboratory monitoring. Most of the evidence in HIT is grade IC, and thus the best evidence is provided by clinical experience. New anticoagulants and platelet inhibitors may offer future alternatives in the management of HIT, but the current treatment options provide the best experience and benefit. The joint clinical and laboratory guidelines provided in this article along with two practical case scenarios were prepared by a Nordic expert panel. They will be valuable for hematologists and colleagues who do not routinely encounter HIT.

Increased coagulation factor VIII, IX, XI and XII activities in non-alcoholic fatty liver disease.

BACKGROUND AND AIMS: Obesity and the metabolic syndrome are established risk factors of venous thromboembolism. As most coagulation factors are produced exclusively by the liver and non-alcoholic fatty liver disease (NAFLD) is tightly related to metabolic disorders, we aimed at studying the association of liver fat with various coagulation factor activities. METHODS: Plasma prothrombin (PT) and activated partial thromboplastin time, activities of vWF:RCo, FVII, FVIII, FIX, FXI, FXII, FXIII, fibrinogen and D-dimer concentrations were measured in 54 subjects with and 44 without NAFLD diagnosed by proton magnetic resonance spectroscopy. Subjects were recruited retrospectively for metabolic studies in our laboratory. The body composition and features of insulin resistance were measured in all subjects. RESULTS: FVIII (107±30 vs. 84±22%, P<0.001), FIX (110±14 vs. 94±16%, P<0.001), FXI (109±16 vs. 96±19%, P=0.001) and FXII (113±21 vs. 99±32%, P=0.002) activities were consistently elevated in subjects with as compared with those without NAFLD. Liver fat percentage was positively related to FVIII (r=0.28, P=0.005), FIX (r=0.36, P=0.0003), FXI (r=0.29, P=0.004) and FXII (r=0.30, P=0.003) activities, again independent of age, gender and body mass index (BMI). PT%, vWF:RCo activity and fibrinogen were higher in subjects with as compared with those without NAFLD, but this difference disappeared after adjusting for age, gender and BMI. CONCLUSION: FVIII, FIX, FXI and FXII activities are increased in human NAFLD and correlate with the features of insulin resistance. The relationships between NAFLD and these coagulation factors are independent of age, gender and BMI, suggesting that the fatty liver can contribute to the risk of thrombosis.

Unaltered blood coagulation and platelet function in healthy subjects exposed to acute hypoxia.

INTRODUCTION: Acute hypoxia has been suspected to cause blood coagulation and platelet activation. Our aim was to study blood coagulation and platelet function during a short hypoxic exposure. METHODS: Healthy nonsmoking men (N = 10) inhaled a normobaric hypoxic gas mixture containing 8% of oxygen (92% nitrogen) for 7 min via a face mask. Venous blood was collected 5 min before and during the 5 to 7 min of hypoxia exposure (i.e., pretest and hypoxia samples, respectively) while monitoring arterial oxygen saturation (SaO2) with pulse oximetry. Blood sampling was completed in 2 min and the face mask was removed. Venous epinephrine and norepinephrine, complete blood counts, and a panel of coagulation markers were analyzed. Platelet aggregation induced by ristocetin, adenosine diphosphate (ADP), arachidonic acid, and thrombin receptor activating peptide was studied with Multiplate and shear force-dependent functions with PFA-100R (collagen/epinephrine and collagen/ADP cartridges), both assays in whole blood. RESULTS: During hypoxia, SaO2 declined from 98 to 58% (ranges 97-99% vs. 42-85%), while heart rate increased from 69/min to 94/min (SD 11 vs. SD 13). Venous epinephrine and norepinephrine levels also increased. This short hypoxia induced minor but uniform increases in red cells, reticulocytes, and leukocytes and decreases in platelet counts. Plateletfunctions and prothrombin time, APTT, thrombin time, D-dimer, fibrinogen levels or von Willebrand factor (VWF), antithrombin, factor V (FV) or FVIII activities did not change. DISCUSSION: Profound acute hypoxia failed to affect blood coagulation or platelet functions in healthy individuals.